Description of the Related Art
An example of a data communication system in a multi processor system according to the prior art is disclosed in Japanese Patent KOKAI JP-A-8-16540, which describes a method of communicating data between processors. Specifically, the specification proposes a message communication system in which each element processor has message receiving means for writing received messages to a memory area, which is provided for this element, in the order in which the messages arrive, and remote writing means for writing data directly to a memory area of a shared memory. At transmitting processor element uses the remote writing means to write the body of a message, which is to be transmitted to a receiving processor, to the shared memory, and transmits information identifying the message as well as pointer information pointing to the body of the message to the message receiving means of the receiving processor element.
In this message communicating method according to the prior art, transmitting/receiving is carried out in such a manner that the transmitting processor writes a message or part of the message via a communication buffer and the receiving processor reads in the message via the same communication buffer. However, the size of the communication buffer that can be secured in memory has an upper limit. If a message whose size is decided by user requirements exceeds the size of. the communication buffer, the transmitting and receiving processors repeat the same processing a number of times to transmit and receive parts of the message via the communication buffer.